1-Are there tensions nowadays between the former yugoslavian republics? 2-What is the current political economic and social state of modern former Yugoslavian republics?
Yes. While some relations have normalized, there are tensions between several states of former Yugoslavia, most importantly because many aspects of the former republic and subsequent war have been neglected until today. Some of these tensions heightened because of the refugee crisis.
Croatia–Slovenia relations are riddled with tension, be it over history, fishing rights, Yugoslavian banks. The shared border is heavily debated even today. In July 2015 Croatia withdrew from arbitration at the Permanent Court of Arbitration, The Hague. To stop refugees, Slovenia built a fence at the (controversial) border, creating a precedent for the line of the border and (understandably) upsetting Croatia.
Croatia–Serbia relations are burdened by Yuglosavian history; the question of who is responsible for war and war crimes, e.g. the displacement of the Serbian minority in Croatia.
Serbia–Kosovo relations are obviously burdened by history, e.g. ethnic tensions post Kosovo independence. In 2013, however, both states signed a declaration of normalization, since both countries want to join the EU. Even now, however, Serbia doesn't recognize Kosovo.
In general, though, all states are on a good way. The possibility of joining the EU provides incentive for all states to improve relations (eg Brdo-Brijuni process).
- Croatia and Slovenia as EU-members are best off. The most recent EU progress report highlights that all states are making good progress politically and economically, but problems remain such as corruption, independent judiciarys, so they have a long way to go still to reach EU norm.